<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="./lib/vue-2.4.0.js"></script>
    <style>
        .thin {
            font-weight: normal;
        }

        .red {
            color: red;
        }
    </style>
</head>

<body>
    <div id="app">
        <h1 :class="['thin','red']">{{ msg}}</h1>
        <h1 :class="objClass">{{ msg}}</h1>
    </div>
    <script>
        var vm = new Vue({
            el: '#app',
            data: {
                flag: false,
                msg: '123455',
                objClass: {
                    thin: true,
                    red: false,
                },
            },
            methods: {

            },
        })
    </script>

</body>

</html>